With the development of Internet and wireless Internet technology, traditional publishing industry is transformed into electronic publishing which, along with electronic books, has prevailed in the industry. There are three main formats of electronic books at present, namely, PDF format, ePub format (i.e. a zip package of HTML webpages) and Mobi format (regarded as a simplified PDF format). Amazon is replacing Mobi with new KF8 format that can support HTML5.
The above three formats may be divided into two categories. The first category involves electronic documents whose format and layout cannot be rearranged, such as electronic documents in PDF format. The second category involves electronic documents whose layout can be automatically rearranged in terms of resolution of a reader, such as electronic documents in ePub format. However, the document format that supports automatic rearrangement of the electronic documents according to the resolution of the reader is devoid of concept of page number, i.e. displaying inconsistent results on various terminal carriers. Moreover, for a little more complex layout, the automatic rearrangement effect is poor. For lack of page numbers after the automatic rearrangement, it is difficult to communicate and collaboratively edit the electronic documents of this kind.
As for the document format that does not support rearrangement, for example, PDF format may support any complex layout, but the layout cannot be rearranged automatically after the initial arrangement is completed, and hence the display effect is poor by automatically zooming in and out. Moreover, this kind of document format does not allow collaborative editing.